The purpose of this project is to first study the osmotic behavior of platelets and other blood components during the introduction and removal of cryoprotective agents (CPAs) from both an experimental and analytical point of view and then to develop optimum CPA introduction/removal protocols which can be readily employed in blood banks. Currently, the osmotic response and functional integrity of platelets and other blood components are being experimentally observed by scientists at the Cryobiology Laboratory of the American Red Cross Blood Research Laboratory. At NIH, the theoretical predictions of cell behavior during CPA introduction and removal based upon a previously developed nonsteady state mass transfer model are being compared to the experimental observations of the responses of cells to changes in the composition of their suspending media. This correlation of our experimental and analytical findings permits the relevant transport parameters (e.g. cell water permeability, cell solute permeability and cell solute reflection coefficient) to be deduced. On the basis of these results, a modified dialysis system which will be capable of altering the CPA content of platelets and other blood components in a controlled manner is also being designed. With such a system and a previously developed theoretical method for optimally introducing and removing CPAs, it is hoped that osmotic stresses and strains imposed upon cells during conventional introduction/removal protocols can be minimized.